NZR RM class (Wairarapa)
The NZR RM class Wairarapa railcar (or Rimutaka railcar) was the first truly successful class of railcars to operate on New Zealand's national rail network. They entered service in 1936 and were classified RM like all other classes of railcars in New Zealand; they came to be known as the 'Wairarapa' class (and sometimes as the 'Rimutaka' class) as they were designed to operate over the famous Rimutaka Incline to the Wairarapa region. They also acquired the nickname of "tin hares" in New Zealand railfan jargon. The first two to be introduced re-used the numbers RM 4 and RM 5 that had previously been used by the withdrawn experimental Model T Ford railcars.
Background
The Rimutaka Incline over the Rimutaka Ranges posed a severe time delay to any service operating between Wellington and the Wairarapa region. At one end of the incline, a train had to have its engine replaced by multiple members of the H class, as the H class locomotives were specially designed to work the steep and difficult incline. Once they hauled the train the length of the incline, they were then replaced by a single ordinary engine, and the procedure to attach and remove the H class locomotives as well as the actual trip along the Incline was tremendously slow.
The Wairarapa railcars were designed as an answer to this problem. They were intended to operate along the length of the Incline and take over Wairarapa passenger services from regular carriage trains. In design, they resembled a bus, and unlike a usual single-wagon railcar that has a driving compartment at each end, the Wairarapa railcars only had one driving end, necessitating that they be turned at the terminus of their journey. One characteristic of the Wairarapa railcars' design was that their body had to be built higher to easily nagivate the Fell centre rail on the Rimutaka Incline.
Operation
Upon their introduction to service in 1936, the Wairarapa railcars proved to be the first successful class of railcars in New Zealand, although it is arguable that only the financial constraints of the Great Depression thwarted the success of the earlier Edison battery-electric railcar. The Wairarapa railcars immediately slashed running times between Wellington and the Wairarapa, and would operate the full length of the Wairarapa Line from Wellington to Woodville, and then through the Manawatu Gorge to Palmerston North. They proved popular with passengers, fully replacing a locomotive-hauled carriage train known as the "Wairarapa Mail" in 1948, though local "mixed" trains that carried both freight and passengers continued to operate.
Withdrawal and preservation
The replacement of the Rimutaka Incline by the Rimutaka Tunnel in November 1955 meant that the main reason for the Wairarapa railcars' operation ceased to exist. Locomotive hauled trains were now competitive in timings with the railcars and they were soon withdrawn.
Most of the railcars were eventually cut up for scrap, but one was saved by the Pahiatua Railcar Society. It was rescued in a considerably run-down condition, but is now being restored with the intention of returning it to full operability.
